The production of 1,5-substituted tetrazoles by addition of an organic azide to a nitrile was extended from intramolecular cyclizations to intermolecular additions by Carpenter, J. Org. Chem. 27, 2085(1962) with the discovery that activation of the nitrile by electron-withdrawing groups (per haloalkylnitriles) afforded facile reactions without a catalyst. It was previously known that attempts to saponify 5-carboethoxytetrazole led directly to the unsubstituted 1H-tetrazole, presumably because the 1H-tetrazole-5-carboxylic acid was unstable, spontaneously decarboxylating to the unsubstituted product, Oliveri-Mandalia, Gass. Chem. Ital. 41, 59 (1911). Recently, Katner disclosed in U.S. 3,962,272 a new procedure for producing 5-acyl-1H-tetrazole-1-acetate esters by reaction of an acyl cyanide with azidoacetic acid or ester at elevated temperatures.